Grinding machine



Nov. 10, 1953 ow 2,658,313

GRINDING MACHINE Filed Nov. 23, 1949 3 Sheets-Sheet l ALFRED J BOWEN 95/02 IN VEN TOR.

92 I BY Nov. 10, 1953 J, ow 2,658,313

GRINDING MACHINE Filed Nov. 23, 1949 3 Sheets-Sheet 2 BY I I I I8 MM 2420 57 Nov. 10, 1953 A. J. HOWEN GRINDING MACHINE Filed Nov. 25, 1949 3Sheets-Sheet 3 INVENTOR. ALFRED J BOWEN ATTY Patented Nov. 10, 1953UNITED STATES PATENT OFFICE GRINDING MACHINE Alfred J. Bowen, Beloit,Wis.

Application November 23, 1949, Serial No. 129,149

23 Claims. 1

The present invention relates in general to grinding machines and morein particular to machines known as surface grinders and adapted to grindaccurately finished surfaces on parts of various sizes and shapes suchas may be held by suitable chucks or work holders during the grindingoperation.

My improved grinding machine is characterized by a horizontal bed onwhich one or more work supports may be mounted, a vertical columnextending upward from the bed, a master bearing member rotatably andslidably supported on the column and carrying in balanced relation agrinding wheel assembly on one side and a driving motor On the oppositeside, and mechanism for raising and lowering the bearing member on thecolumn in order to adjust the grinding wheel relative to the work.

The object of the invention is to provide a new and improved grindingmachine of the foregoing type.

A special feature of the invention is an automatic control arrangementfor performing a predetermined grinding cycle on a part held by arotatable work support, the arrangement including an automatic feed forthe grinding wheel and automatic latching and releasing mechanism forthe grinding wheel assembly which maintains it in operative relation tothe work during a grinding cycle and restores it to a non-interferingposition at the end of the grinding cycle to enable the operator toremove the finished work piece and replace it with the next piece to .beground.

The foregoing and other features are described in detail hereinafter,reference being made to the accompanying drawings, in which- Fig. 1 is afront elevation of a grinding machine embodying the invention, includinga section through the base and certain other parts on the line ll-|, ofFig. 2, and a section through the rotatable work support on the line I,Fig. 2;

Fig. 2 is a section on the line 22, Fig. l, and is essentially a top orplan view of the machine;

Fig. 3 shows a cam which forms part of the automatic feed mechanism;

Fig. 4 is a section through the master bearing member on the line 4-4,Fig. 1;

Fig. 5 shows a latch mechanism which is part of the automatic control;

Fig. 6 is a partial section on an enlarged scale on the line 66, of Fig.2;

Fig. '7 is a diagrammatic circuit drawing showing the electricalequipment and wiring thereof;

Fig. 8 is an enlarged view of the micrometer indicator and part of themicrometer dial; and

Fig. 9 is a view of the work rotating mechanism as seen from the rightin Fig. 1.

Referring to the drawings, the reference character I0 indicates acircular base having an upwardly extending rim I l. The rim has anannular interior recess for receiving the large flanged ring l2, the twoforming a reservoir for coolant. An overflow pipe I3 serves to drain thecoolant into a sump (not shown) in the subbase I l. The circulatingsystem for coolant may be of known character and has been omitted inorder not to complicate the drawings.

The subbase is preferably rectangular in horizontal section and rests onthe floor or other support for the machine. It is flanged at the topwhere it supports the base Hi. The base may be secured to the subbase bymeans of countersunk screws such as I5. The base and subbase may be ironor steel castings, and the former preferably has an accurately finishedhorizontal interior surface It on which work holding chucks or otherdevices may be mounted. A known form of magnetic chuck I1 is shown inFig. 2.

The base [0 has an opening at the center thereof, surrounded by anannular recess. The hollow vertical column [8 has a flange at the bottomwhich rests in this recess. The column is secured in position by screwssuch as [9 which pass through the flange and are threaded into the base.The upper portion of the column I8 is somewhat reduced in diameter andhas a finished exterior surface for reception of the master bearingmember 20.

The bearing member 20 is seen in elevation in Fig. 1 and in horizontalsection in Fig. 4. It comprises a casting having finished interiorbearing surfaces engaging the exterior surface of the column I8. Theinside diameter of the bearing member is enlarged for some distanceabout midway between its upper and lower ends to provide an annularspace 2| which is packed with grease. The left hand wall of the bearingmember is divided by a vertical slot 22, Fig. 4, which is filled by acompressible strip 23 of wood or other suitable material to prevent theescape of grease. The

vertical slot 22 is bridged by three cap screws such as 24 by means ofwhich the bearing member may be. adjusted to a very close fit on thecolumn 18. These screws also afford means for taking up wear; if anyoccurs.

For the major portion of its length downward from the top the bearingmember 20 is square in cross section. From a point just below the lowercap screw 24, however, the bearing member is round, forming a shoulderindicated at 25, Fig. 1. The rounded portion of the bearing memher isindicated at 26. The plate 21, seen also in Fig. 2, has an opening forthe rounded part 2G 01' the bearing member and rests against theshoulder 25, where it is secured at the four corners of the bearingmember by screws such as 29. The late l l extends to theright nearly asfar as inner w n or ring,- where itsupiports th'e' curved apron tr guardas. The handle 30 is provided for use by the operator in rotating thebearing member and part supported thereby on the column l8, as will beexplained herein after.

The reference character 4| indicats a Wm!- drical guard which is securedto the rounded lower end 26 of the bearing member 20 by screws such as42 and extends downward around the column I8 as shown.

The reference character 1| indicates showing for thegrinding. wheelspindle and i shown, in 8.11 also in dotted lines in Fig. 2. The housingis rectangular in cross sectionand is provided with vertical flanges,such as 32 through which cap screws suchas 33.extend,to clamp thehousingto the bearing member 28. 'I'heupper end ol the housing is shownin section in Fig. 6, from which it yvlllbe seen that thehousing ispivotally supportei betore the screws 33 are tightened, on the. stud 34the base of which is fixed in a hole hijhe bearing member 2,9. The holesin the flanges 31 thr ough which the screws 33 pass are slightly largerthan the screws, which makes it pos ible to adiustthehousin about thestud 34 aq a .pivotjo align the grinding wheel spindle wi ht cco wmnifl..l '1fhe hollowspindle in cated at 35, Fig. 6, rotatably mounted in avertical channel Q5 inhousing 31 by means of theball bearing 31 at thetop and vor re or more ball bearings (not at the lower end of channel36. The mannel is closedabove bearing 31 by means of thesrqared c n ilandme flan ed olla 3.9. the latter havinsa pr es s ,nt on the spindle35 and helm. rotata le he ew th. The pulley is suitab s c d, n. t es inde 3 shits upper n t ia q er and the s ndlecarri s the rind- 1 8., Pinealh ch.can he s nin ig.1. he

m s Wh e tem a ly sec dto the spin- 9. a k iqwn manner. d ail whi ha o 5PW?! sm ai y $9. m. 3 Pa t th invention- Th sxi insnhee is gnc os d a po ti si rdliw h i atta e to t wer. end

of the member 46 which turn is slidably e eled. 9. the mu i 3 I 'Iham me m fidii d e at yato. th m s n I y a a {time a ran emen p t d h han e 1in rdertor ai sethe guard 45 as the grinding wheel 44 wears away. Thedetails are not shown they form no part oithe invention. It will notedthat. the, plate 21 has an opening for the guard 45 and the grindingwheel 44. Tne motor. is mounted on thebearin mem ber il qppositethejhousing 3|. ,Themo'unting Arrangement comprises a plate 5|, Fig. 4,to whichthe base of the motor is attached, and a bracket 52 which issuitably secured to the bearing member 20. The plate and bracketareproyided with operlapping ears throughwhich holes 'arejdrilled toreceive the pivot rod 53. A pulley I4 is mounted on the motor shaft "andis connected with the pulley 43, on.the grinding wh'eel spindle byybelts 5 5 and S6. The belts are shown in dotted lines in Fig. 1 and alsoappear in-Fig. 76 ward movement of 4 6. They pull the motor and mountingplate ll toward the bearing member 20 and against a stop 51, comprisinga stud 51 which is threaded into the bearing member. This stud aflordsmeans for adjusting the tension 01' the belts.

The mechanism for adjusting the bearing member 20 vertically on thecolumn l8 includes the flanged nut 60 and the micrometer screw ll. shownin Fig. 6. The upper portion of the nut estates through a ml in th'cl'r'cdar plate 02 whim rests against the flange on the nut and isrigidly secured thereto by means of screws such as 63. The plate 62 ispositioned in a recess at thqtop pf the bearing member 28, where it issecured by screws such as 64. Thus the nut BI is firmly attached to thebearing member 20.

micrometer screw 6| is threaded in the nut 60 extending for somedistance above and below the same in the position in which the parts areshown, and is provided with a thrust bearing 65 at its lower end. Thebearing is supported on the disc or ring 65, and the latter normallyrests on the shoulder 61 of the interior wallofthe hollow column l8, 7The shoulder is formed by enlargement of the bore of the column whichextends a short distance down from thetopal shown. As will be explainedpresently.- the disc 66 may be raised off the shoulder 61(as it is shownin thedrawing) and lowered thereto by csn qf het b la m be I Themicrometer screw 6] is rotated by megnl of the hand wheel 10, seen bestin Fig. 2. The hand, wheel has arim of large diameter, which enables itto be reachedeasily by the operator. and acentralhubjl to which the rimis connected by spokes as shown. The hub 1| is secured to the top of thetubular member 12 which surround the upper portion of the micrometerscrew II and is provided with a flange 18 at its lower end. Themicrometer dial is indicated at 14 andhasa central hub 15 which fitsover the member 12 and rests, against. the top of the flange 18; Beneaththe flange 18 there is a split ring 16 which lies partly in a grooveformed in the nut 68 near the upper end thereof; being rotatable on thenut. The parts are held together by means 01' mm suchas 11 and 18 whichpass through holes in the hub ,15'and name: 18 and are threaded into thering 16. Summing up the foregoing, it will be seen that the hand wheel18 and the micrometer dial 15 are rigidly connected by means of thetubular member 1! and that these parts are rotatably mounted on the nut60 (and thereby on the hearing member 20) by means of the split ring 10.This ring may be made in two overlapping sections so'that it can beassembled in the gm" m the nut 60.

The driving connection between the hand wheel and the'mic'rometer screw8| comprises two key: 88 and 81, shown in dotted lines in Fig. 2. Thekey '80 is also seen in Fig. 6. These keys are fixed in slots or kywaysin the tubular member 12 and are slidable in keyways such as 82 in themicrome'ter screw Bl. As we are shown in 6, the keys extend downwardabout half way into the k'eyways s2. Rotation oi the hand wheel rotatesthe micrometer screw 61 in the not Ill and raises or lowers the bearingmember 10 on the column I8, dependmg on the direction of rotation, thekeys to and 84 sliding in the keyways 82 during such movement. In itslower most position the lower end or the bearing member engages theshoulder ll, Fig. 1, on the column I 8. No stopi's necessary to limittheir]:-

the bearing member. It'mlw be noted, however, that the keys an and 8|will leave the keyways 82 in the micrometer screw before the screw canbe turned downward clear through the nut, which makes further rotationof the hand wheel in this direction ineffective and accordingly limitsthe distance through which the bearing member may be raised by rotationof the handwheel.

It may appear that rotation of the hand wheel would have a tendency torotate the bearing member 20'and all associated parts about the columnI8, the entire assembly being supported on the thrust bearing 65. It isindeed possible to accomplish this by a very careful and gradualapplication of force to the hand wheel. In the normal operation of thehand wheel, however, the hand wheel rotates relative to the bearingmember and turns the micrometer screw 6| in nut 60 as described, duepartly to the friction between the bearing member 29 and column I8 andpartly to the great inertia of the bearing member and the heavy partssupported thereon. When the hearing member assembly is rotated in thecourse of the operation of the machine, by means of handle 30, forexample, the entire assembly including the hand wheel and micrometerdial rotates as a unit, on the thrust bearing 55.

The plate 84 extends over the motor 50 and housing 3| and is attached tothe top of the bearing members 20 by means of countersunk screws. Itwill be appreciated that since the plate 62 is circular there is ampleroom at the four corners of the bearing member for these screws. Theplate 84 has openings therein for the motor shaft, the micrometer screw6| and parts associated therewith, and the spindle 35. These openingsare indicated in Fig. 6, except the opening for the motor shaft.

The belt guard 85 is shown in Figs. 1 and 2. This guard encloses thebelts 55 and 56 and rests on the plate 84 to which it is secured byscrews such as 80, Fig. 6. The guard is notched in front and rear forthe micrometer dial 14, which extends outside the guard, and has anopening at the top for the tubular member I2 which supports the handwheel I above the guard. The threaded nipple 81 is mounted on the guardas shown in Fig. 6 and is part of the circulating system for supplyingcoolant to the hollow spindle 35 which carries the grinding wheel 44.

The micrometer dial I4 is calibrated on its periphery and cooperateswith an index member 88 which is mounted on the guard 85. This indexmember and part of the dial are shown on an enlarged scale in Fig. 8.The scale divisions on the dial are properly related to the pitch of themicrometer screw 6|. The pitch of the screw may be 20 threads to theinch, for example, so that one complete rotation of the hand wheel willraise or lower the bearing member assembly /20 or .050 of an inch. Themicrometer dial may then have 50 scale divisions, each corresponding toa movement of .001 of an inch. The dial is relatively large and thescale divisions are far apart so that each division could be dividedinto smaller divisions, each corresponding to .0001 of an inch. It ispreferable, however, to place these finer scale divisions on the indexmember 88. as shown in Fig. 8.

It may be noted at this point that the driving connection between thehand wheel I0 and the micrometer screw 6| is substantially direct, theonly relatively movable parts being the parts included in the slidingconnection with the screw. The keys 80 and 8| are carefully fitted tothe keyways in the screw to eliminate play and the backlash as read onthe micrometer dial does not exceed about .0002 of an inch.

The rotatable work support may be of any suitable construction,depending on the nature of the parts to be ground. It may have a. chuckor collet, for example, for holding the parts. As shown herein, however,the work support is relatively simple, being adapted to support circularspacers or washers such as 90, and comprises a housing 9| and a flangedshaft 92 rotatably supported therein by means of bearings 93 and 94. Thelower end of the housing 9| extends through an opening in the base I0and a flange on the housing is received in an annular recess surroundingthe opening, where it is secured by screws as indicated. The side wallof the subbase I4 is cut away beneath the opening in the base I0 toprovide room for the lower end of the housing 9| and shaft 92 and forthe pulley 95 which is secured to the lower end of the shaft by the nut96. As its upper end the shaft 92 has an accurately finished horizontalsurface for supporting the work piece 90, which as previously mentionedmay be a spacer or washer, which is to be ground to the requiredthickness. spacer and other similar spacers to be ground mayconveniently be provided with two small. holes for receiving two pinswhich project upward from the finished surface at the end of the shaft.The reference character 91 indicates a guard which is provided toprotect the bearing 93 against the entrance of dust and debris producedby the grinding operation.

The driving motor for the work support is indicated at I00 in Figs. 1and 9. The motor is supported on the housing IOI which contains speedreducing gears for connecting the motor shaft with the output shaft I02.The housing |8I is secured to the wall of the subbase I4 in the properposition as shown in Fig. 1. A pulley I04 is mounted on shaft I02. Thebelt I03 is carried on pulleys I04 and 95 and serves to connect theshaft I02 with the shaft 92.

The mechanism for raising and lowering the bearing member 20 andassociated parts on the column I8 during an automatic grinding cycleincludes the tubular member 68, also referred to as the elevatingsleeve. This sleeve is contained within the hollow column I8 and hasbearings above and Ibelow on the interior wall of the column in which itis slidable vertically. The sleeve 88 is closed at the lower end by theplate or disc I05.

The elevating lever I09 is pivoted on the bracket I0'I which has athreaded extension by means of which it is fastened to the base ID. Thelever I09 may be bifurcated or slotted at the ends for reception of theflattened end of bracket I07 at the right and the roller or follower H0at the left, also the roller I08 which is engaged by the closure plateI06 of the elevating sleeve 68. The roller I08 is located only a shortdistance to the left of bracket IN, the ratio of the long arm of thelever to the short arm being about 3 to 1.

The driving motor for the elevating mechanism is indicated at I I2. Thismotor is supported on the housing I I3 which is attached to the wall ofthe subbase I4 as shown. The housing 3 contains speed reducing gears forconnecting the shaft of motor II2 with the output shaft M4 to drive thelatter at a slow speed, which may be, for example, about 2 rotations perminute. The cam II6, shown on an enlarged scale in Fig. 3;

This

7 ismmmtedcnthematt il4andcooperatuwith roller ileforopenting the leverI50. Thchcusing I I1. supported on the wall of'subbase I4, cm.- tains anormally open switch which is operated wean III byrnemofalevermechanismin during each rotation of the shaft I.

AsshownmFig.2,thereisasprmg I2lwhich normally holds the edse of theapron 20 against the stop III. In this position, thebearing memberassembly including the grinding wheel 44 is rotated about 30 degrees ina counterclockwise direction from the positim in which it is shown inFig. 2. This leaves the rotatable work support 02 fully exposed andaccessible to the operator.

When the operator rotates the bearing member assembly in a clockwisedirection by means of thehandle 20 to the position in which it is shownin Fig. 2, it becmnes locked by a latching mechanism. This mechanism ispartly enclosed in a homing I22 secured to the flanged upper rim of ringI2 and is so oriented that when the bearing member is in latchedposition the path of the grinding wheel 44 is directly above the centerof the shaft 92 and the work piece 90 supported thereon.

Details of the latching mechanism are shown in Pig. 5. It comprises aframe I23 secured to the ring I2, a latch I24 which is pivotally mountedon the frame, and a catch I25 attached to the apron 25 and adapted tocooperate with the latch I24 as shown to hold the assembly in position aainst the pull of spring I20. It will be noted that the latch I24 isurged into operative engagement with the catch I25 by the spring I26.The solenoid I20 is mounted on frame I23 and is adapted,- whenenergized, to rotate latch I24 on its pivot to release the catch I25.This permits the grinding wheel assembly to be rotated by the spring I20until its movement is arrested by the stop I2I. When the solenoid I20 isdeenergized, the ensuing rotation of the latch I24 by the spring I25causes it to engage the operating member I29 of a normally closed switchI21 and open it. These operations will be explained more fully inconnection with Fig. '7.

Referring now to Fig. 7, the reference character 8 indicates the mainswitch, through which three-phase alternating current is supplied to theconductors I4I, I42 and I43 and thence to the motors =50, I and H2 undercontrol of relays I44 and I45. These relays may Ibfi of any suitableconstruction, adapted to operate on alternating current, and are shownin conventional manner. The switches SI and S2 are stop and startswitches, respectively, and are also shown conventionally. Other partsshown in the circuit drawlng have already been described.

It will be understood that the switches SI and S2 may be mounted insuitable manner on the base of the machine, where they will beconvenient to the operator. These switches and the wiring are not shownin the mechanical drawings. Fig. 1 does, however, show the conduits I50and II for the conductors I55 which supply current to the motor 50. Theconduit I50 is supported on the base III by a clamp I52 and on theflanged ring I2 by the bracket I53. The conduit ISI is supported on theplate 84 by a holding device I54. The upper ends of the conduits areabove the center of column I 8 and are spaced apart for a shortdistance, where the conductors I55 are unconfined. These conductors areflexible and the arrangement thus provides for about 8 I 180 degreerotation of the grinding wheel assembly about the column It It will beappreciated, however, that the machine is inherently adapted forcontimrws rotation of the grinding wheel assembly about column I5.

The operation of the machine will now be explained, it being assumed forthis purpose that the machine is to be used for grinding finishedsurfaces on spacers such as 50. Some preliminary adjustments which haveto be made on setting up the machine will first be explained.

The cam I" is designed in accordance with the particular grinding Job tobe performed, although of course a given cam may be used on differentjobs if conditions permit. Several cams may be provided and are readilyinterchangeable. In the present case it may be assumed that the maximumamount of material which has to be removed on any spacer to reduce it tothe required thickness is about .030 of an inch. The total lift of thegrinding wheel should then be about .050 of an inch, in order to aflordthe necessary clearance between the work and the wheel as the latter ismoved to grinding position. The total rise on the cam should besuflicient to produce the indicated lift 01' the grinding wheel plus anadditional amount which is necessary in order to insure that during thespark out period the thrust bearing 55 will be supported on the shoulder51 in column I8 rather than on the cam. It is preferable to allow about.005 of an inch clearance between the roller I00 and the plate I 06 whenthe cam follower H0 is resting on the spark out section of the cam inorder to insure that the above condition will obtain.

Since the roller I00 is located in the subbase where it is not veryaccessible the clearance may be measured by means of a thickness gaugeinserted between the cam and the follower IIO, making due allowance forthe difference in the length of the lever arms of lever I00. If the camis not in the proper position, the machine is started in the manner morefully described hereinafter and is stopped when the spark out section ofthe cam comes into engagement with the follower. The clearance is thenmeasured and if any adjustment is required it is accomplished by raisingor lowering the housing II3 on the subbase I4. The housing is secured tothe subbase by cap screws which extend through slots in the flanges orfeet of the housing which rest against the subbase so that theadjustment can be made as described.

The grinding wheel is adjusted relative to the work with the camfollower IIO restin on the dwell section of the cam, as it is shown inFig. 1. With the parts in this position, and with a work piece or spaceron the work support 92, the grinding wheel is lowered by means of thehand wheel 10 until it clears the top of the spacer 90 by about .020 ofan inch. The grinding wheel assembly should be in latched position abovethe work support while the adjustment is being made and after it iscompleted the latch I24 can be released by hand to permit restoration ofthe grinding wheel to normal position with the edge of apron 28 againstthe stop I2I. It will be understood that the adjustment of the grindingwheel as well as the adjustment of the cam is made with the main switchopen and the motors inactive, the power bein applied only to rotate thecam to the proper position when necessary.

The machine being ready, the operator starts grinding operations byclosing the main switch S again, after which he operates the startswitch S2 momentarily and then rotates the grinding wheel assembly togrinding position by means of the handle 30, where it is held by thelatch I24. The closure of the main switch supplies current to theconductors I 4|, I42 and I43. The operation of the start switch closes acircuit for relay I45 in an obvious manner, bridging the relay acrossthe conductors II and I43. Upon energizing, relay I45 establishes aholding circuit for itself at contact I46 and at its three uppercontacts it extends the three conductors I4I, I42 and I43 through to themotor 50, which starts to run and rotate the grinding wheel 44.

When the catch I25 becomes locked by the latch I2 3, the latter isrotated sufiiciently to permit the switch I21 to close, therebyestablishing a circuit for relay I44. Upon energizing, relay I44 closesthe three conductors I4I, I42 and I43 through to the motors I59 and I I2and these motors begin to run. Motor I rotates the shaft or worksup-port 92 and the work piece, spacer 90, which is supported thereon.Motor II2 rotates the shaft H4 and the cams II 5 and H6.

In response to rotation of the cam I IS, the cam follower Ht leaves thedwell section of the cam and passes on to the rapid feed section,causing the grinding wheel to be quickly lowered into engagement withthe work piece 90. This is accomplished by the lever I09 and theelevating sleeve 68. Grinding now begins and continues as the grindingwheel is gradually lowered by cooperation of the cam follower with theslow feed section of the cam. Shortly before the end of this section ofthe cam is reached the ring 66 supporting the thrust bearing 55 comes torest on the shoulder 51, which prevents further lowering of the grindingwheel. The cam rotates freely during the spark out period, therefore,while the grinding wheel cooperates with the rotating work sup-port toproduce a finished surface on the work piece 98.

At the end of the spark out period, the cam follower comes intoengagement with the wheel rise section of the cam, causing the grindingwheel to be raised off the work piece by means of lever I89 and theelevating sleeve 68. When the cam follower reaches the dwell section ofthe cam Ilfi, the cam H5 closes the switch II1, thereby closing acircuit for the solenoid I28. Upon energizing, solenoid I28 rotates thelatch I24 to release the catch I25, whereupon the grinding wheelassembly is rotated on the column I8 by the spring I28 until itsmovement is arrested by the stop I2 I. The continued rotation of cam II5 now permits the switch II1 to open, deenergizing the solenoid I28.This takes place while th cam follower I I9 is still in engagement withthe dwell section of cam I i6, Upon deenergization of solenoid I28, thespring I26 rotates the latch I24 to open the switch I21, whereupon therelay I44 deenergizes and stops the motors I00 and I I2. This completesthe grinding cycle.

The operator may now remove the spacer 90 from the work support andmeasure it with a micrometer to determine if its thickness is correct,or within the tolerance limits assigned. Being the first piece ground,it may not be exactly right, so that adjustment of the grinding wheel isnecessary. This can be done very accurately by means or the hand wheel10 while reading the amount by which the grinding wheel is raised orlowered on the micrometer dial 14 and the associated index member 88.

Another s cer u h as ow be place in position on the work support 92,after which the grinding wheel assembly is again rotated to grindingposition by the handle 30. The grindin wheel becomes latched in thisposition as before and the operation of the latch I24 closes the switchI21 to energize relay I44 and start the next grinding cycle.

It will be noted that the work supporting surface on shaft 92 and theshoulder 61 on column I8 are fixed as regards their relative elevation,so that the only variable which can affect the thickness of the finishedspacers is the gradual wearing away of the grinding wheel. The operatortakes this factor into consideration by measuring the finished spacersfrom time to time as they are removed from the work support and bylowering the grinding wheel when necessary.

During grinding operations as described the motor 50 continues to run.If it should become necessary to stop the motor for any reason, this canbe done by operating the stop switch SI to open the holding circuit ofrelay I45. In an emergency the stop switch may also be used during agrinding cycle to stop the other motors.

The grinding machine is adapted for use as a hand operated machine forgrinding work pieces supported on the magnetic chuck I1, or on otherwork supports arranged on the surface I6 of the base I0. In order toprepare the machine for this type of grinding operation withoutpreventing the relatively quick resumption of the grinding operationssuch as previously described, the machine may be stopped with the camfollower III] on the spark out section of the cam I I6 so that thethrust bearing 65 is supported on the shoulder 61. The spring I20 isthen unhooked at the apron 28 and the latch mechanism I22 is unfastenedand moved radially outward where it will not interfere with the catchI21 and the apron 28. The frame I23 of the latching mechanism mayconveniently be provided with an extension I30 which can be screwed tothe flanged rim I2 to hold the latching mechanism in this position.

The foregoing preparations having been made, the grinding wheel I44 maybe rotated into position above the chuck I I1. The motor.50 is startedas previously explained, but the motors I00 and H2 remain inactivebecause the circuit of relay I44 is held open at the latching mechanism,now in inoperative position. Grinding is accomplished by lowering thegrinding wheel on to the work and oscillating the wheel over the work ina manner which will be understood without further explanation.

The invention having been described that which is believed to be new andfor which the protection of Letters Patent is desired will be pointedout in the appended claims:

1. In a grinding machine, a base, a vertical column extending upwardfrom said base, a bearing member rotatable and slidable on said column,a grinding wheel and a driving motor therefor mounted on said bearingmember, a nut disposed coaxially with said column and fixed to saidbearing member, a micrometer screw threaded in said nut, a thrustbearing supporting said screw on said column, a hand wheel rotatablymounted on said bearing member, said hand wheel being disposed in ahorizontal plane with its center on the axis of said column, and adriving connection between said hand wheel and said screw, wherebyrotation of said hand wheel rotates said screw in said nut to raise orlower said bearing member on said column.

2. In a grinding machine, a base, a vertical column extending upwardfrom said base, a bearing member rotatable and slidable on said c.01-unm, a grinding wheel and a driving motor therefor mounted on saidbearing member, a nut disposed coaxially with said column and fixed tosaid bearing member, a micrometer screw threaded in said nut, a thrustbearing supporting said screw on said column, a hand wheel disposedooaxially with said column and rotatably supported on said bearingmember said hand wheel being of relatively large diameter and accessibleirom any point around the machine, a calibrated dial also disposedeoaxially with said column .and fixed to said hand wheel, meansresponsive to retation of said hand wheel and dial relative to saidbearing member for rotating said screw in said nut to raise and lowersaid bearing member on said column, and an index member fixed relativeto said bearing mmnber and cooperating with said dial to indicatethereon the extent 9! such movement.

8. In a grinding a base, .a vertical eolunm extending upward from saidbase, a bearing member rotatable and slidableon said column. a grindingwheel and a driving motor therefor mounted on said member, a nutdisposed eoaxia-lly with said column and fined to said bea.r ing member,a micrometer screw threaded in said nut, a thrust bearing supportingsaid screw, nut, and bearing member on said column, means rctatablymounted on said bearing member for retoting said screw in said nut toraise and lower said bearing member on said column, said means having aconnection with said screw, a circular dial having scale divisionsextending around its periphery, said rotating means supporting said dialcoaxially with said column for rotation with said screw. and an indexmember fixed during such rotation and cooperating with the dial toindicate thereon the extent of the movement of the bearing member.

4. In a grinding machine, a base, a vertical column extending upwardfrom said base, a bearing member rotatable and slidableon said column, agrinding wheel and a driving motor therefor mounted .on said bearingmember, .a nut disposed coaxially with said column :and fixed to saidhear-- ing member, a micrometer screw threaded in said nut, a thrustbearing supporting said screw on said column, a tubular member partlyenclosing said screw and rotatably mounted on said bearing member, anoperating device and a circular calibrated dial supported on saidtubularmember,

said dial being coaxial with said screw and disposed in a horizontalplane, means responsive to rotation of said tubular member by saidoperating device for rotating said :screw in said nut to raise and lowersaid bearing member on said column, and an index member relative towhich the dial rotates during rotation of the screw, said index membercooperating with the dial to show thereon the extent of movement of thebearing member on said column.

.5. In a grinding machine, a base, a vertical column extending upwardfrom said base, a bearing member rotatable and slidable on said column,a grinding wheel and a driving motor therefor mounted on said bearingmember, a nut disposed coaxially with said column and fixed tosaidbearin member, a micrometerscrew threaded in said nut, a thrust bearingsupporting said screw on said column, means vfor rotating said bearingmember and thegrinding wheel mounted thereon about said column as anaxis to br ng the Whi into operative relation to work supported on saidbase, said nut and screw rotating with said baring member, a hand wheelsupported on said bearing member and partaking in such rotation thereof,the supporting means for said hand wheel providing for rotation thereofon the axis of said column independmt of the bearing member, and meansresponsive to such independent rotation for rotating said screw :in saidout to raise and lower said bearing member on said column.

6. In a grinding machine, a horizontal base, a column extendingvertically upward from said base, an assembly comm-mug a bearing memberrotatable and siidable on said column and havingmounted thereon agrinding wheel and driving motor therefor, and means for raising andlowering said assembly on said column comprising a support on saidcolumn and elements including a thrust bearing, a lead screw and a nutthreaded thereon disposed in serial relation on the axis of said eolimm.one of said elements resting on said support and another of saidelements having a connection with said bearing member, an operatingmember having a longitudinally sliding but non-rotative connection withsaid lead screw, and means for rotating said operating member to rotatesaid lead screw in said nut to raise and lower said bearing member onsaid column as set forth.

7,. In a grinding machine, a base, a vertical column extending upwardfrom said base, a bearing member rotatably and slidably mounted on saidcolumn, a grinding wheel assembly including a grinding wheel and mountedon said bearing member for movement in a circular path above said base,a motor mounted on said bearing member for driving said grmding wheel, awork support mounted on said base in the said path, means having aconnection to said assembly and tending to rotate the same to positionsaid grinding wheel at a point angularly spaced from said work support,latching mechanism operating to hold said grinding wheel assembly whenthe same is rotated about said column to a position above said worksupport, and means responsive to operation of said latching mechanism toautomatically lower said bearing member on said column to .feed thegrinding wheel into operative relation to a work piece on said worksupport.

8. In a grinding machine, a base, a vertical column extending upwardi'rom said base, a bearing member rotatably and slidably mounted on saidcolumn, a grinding wheel assembly including a grinding wheel and mountedon said bearing member for movement .in .a circular path above said-base,a motor mounted on said bearing member for driving said grindingwheel, a work support mounted on said base at a point in the said pathwhich is angularly spaced from said grinding wheel, means for rotatingsaid work support, and means responsive to rotation of said grindingwheel assembly about said column to a position above said work supportfor starting the rotation of said work support and for lowering saidbearing member to feed the grinding wheel into operative relation to awork piece on said support said last means including electric motors andcircuits therefor and a switch actuated by said assembly on arrival atsaid position to close said circuits.

9. In a grinding machine, a base, a vertical column extending upwardfrom said base, a bearing member rotatably and slldably mounted on saidcolumn, a grinding wheel assembly including a grinding wheel and mountedon said bearing member for movement in a circular path above said base,a motor mounted on said bearing member for driving said grinding wheel,a work support mounted on said base in the said path, latching mechanismholding said assembly in a position above said work support when theassembly is rotated to such position, means responsive to such rotationfor automatically lowering said bearing member to feed the grindingwheel on to a work piece on said support, means operated in timedrelation to the grinding wheel feed for releasing said latchingmechanism, and means effective upon such release for rotating saidassembly about said column to a position out of alignment with said worksupport.

10. In a grinding machine, a base, a vertical column extending upwardfrom said base, a bearing member rotatably and slidably mounted on saidcolumn, a grinding wheel assembly including a grinding wheel and mountedon said bearing member for movement in a circular path above said base,a motor mounted on said bearing member for driving said grinding wheel,a work support mounted on said base in the said path, and mechanism forsliding said bearing member on said column to move the grinding wheel inand out of operative relation to a work piece on said support, saidmechanism including a vertical member slidably mounted in bearingsinside said column and extending beneath said base, means including athrust bearing supporting said bearing member on said vertical member,and mechanism 'beneath said base engaging said vertical member foroperating said vertical member for the purpose set forth.

11. In a grinding machine, a base, a vertical column extending upwardfrom said base, a bearing member surrounding and rotatable and slidableon said column, a grinding wheel assembly including a grinding wheel andmounted on said bearing member for movement in a circular path abovesaid base, a motor mounted on said bearing member for driving saidgrinding wheel, a work support mounted on said base in the said path, asupport carrying the weight of said bearing member, means acting againstsaid support and having a connection to said bearing member foradjusting the elevation of said bearing member relative to its saidsupport by sliding it on said column to thereby adjust said grindingwheel relative to a work piece on said work support, mechanism connectedto said bearing member through said adjusting means for holding saidbearing member oii its said support during movement of the grindingwheel to a position above said work support, and means for operatingsaid mechanism to lower said bearing member on to its said support toeffect a desired grinding operation on said work piece.

12. In a grinding machine, a base, a vertical column extending upwardfrom said base, a grinding wheel assembly comprising a grinding wheeland a driving motor therefor, said assembly having a bearing on saidcolumn providing for rotative and sliding movement of the assembly onsaid column, a work support on said base in the path of said grindingwheel when the same is rotated about said column, mechanism for raisingand lowering said assembly on said column, means responsive to thegrinding wheel being positioned above said work support for operatingsaid mechanism to lower said assembly on said column and to raise thesame after the lapse of a predetermined time interval to cause thegrinding wheel to remove material from a Work piece on said support,said means including a motor for driving said mechanism and motorstarting means operated by a part of said assembly when said grindingwheel arrives in position above said work support, and means interposedbetween said mechanism and said assembly for preadjusting the elevationof said assembly relative to said mechanism in accordance with the depthof material to be removed.

13. In a grinding machine, a base, a vertical column extending upwardfrom said base, a grinding wheel assembly comprising a, grinding .wheeland a driving motor therefor, said assembly having a bearing on saidcolumn providing for rotative and sliding movement of the assembly onsaid column, a work support on said base in the path of said grindingwheel when the same is rotated about said column, mechanism including arotatable cam holding said assembly in an elevated position to permitthe grinding wheel to be rotated about said column to a position abovesaid work support, means responsive to such rotation for rotating saidcam to lower said assembly on said column to bring the grinding wheelinto engagement with a work piece on said work support and grind thesame, and means independent of said cam supporting said assembly duringthe final stage of the grinding operation.

14. In a grinding machine, a base, a vertical column extending upwardfrom said base, a grinding wheel assembly comprising a grinding wheeland a driving motor therefor, said assembly having a bearing on saidcolumn providing for rotative and sliding movement of the assembly onsaid column, a work support on said base in the path of said grindingwheel when the same is rotated about said column, automatic feedmechanism having a connection to said assembly for raising and loweringsaid assembly on said column, said mechanism normally holding saidassembly in raised position to permit said grinding wheel to be rotatedabout said column to a position above said work support, means includinga device actuated by said rotation for operating said feed mechanismthrough a cycle of predetermined duration to perform a grindingoperation on a work piece on said work support by lowering and thenraising said assembly, and means independent of said feed mechanismsupporting said grinding wheel at a fixed distance above said work pieceduring the final stage of said grinding operation.

15. A grinding machine as claimed in claim 14, characterized by theprovision of a cam forming part of said feed mechanism, said cam havinga dwell section for supporting the assembly during rotation thereof toposition above the work sup port, a rapid feed section to start thegrinding operation, and a slow feed section to continue the grindingoperation up to the final stage.

16. In a grinding machine, a base, a vertical column extending upwardfrom said base, a grinding wheel assembly comprising a grinding wheeland a driving motor therefor, said assembly having a bearing on saidcolumn providing for rotative and sliding movement of the assembly onsaid column, adjustable means supporting the weight of said assembly tocontrol said sliding movement, a Work support on said base in the pathof said grinding wheel when the same is rotated about said column,spring means nor mally maintaining said grinding wheel assembly in aninoperative position relative to said work support, a stop determiningsaid position, means locking the grinding wheel assembly in operativeposition above said work support when rotated in such operativeposition, and automatic control means connected with and adapted tooperate said adjustable supporting means for lowering and raising thegrinding wheel to perform a grinding operation on a work piece on saidsupport, said control means including means for releasing said lockingmeans upon the completion of said grinding operation.

17. In a grinding machine, a base, a vertical column extending upwardfrom said base, a bearing member rotatably and slidably mounted on saidcolumn, a grinding wheel mounted on said bearing member for rotation ona vertical axis spaced from said column, said wheel being movable in acircular path above said base by rotation oi said bearing member aboutsaid column, means sustaining the weight of said bearing member duringrotation thereof about said column, said means comprising a nut disposedcoaxially with said column and fixed to said bearing member, amicrometer screw threaded in said nut and a thrust bearing disposedbetween said screw and a support connected to said base, an operatingdevice for rotating said screw in said nut to raise and lower saidbearing member on said column, said device being mounted on andpartaking in the movements of said bearing member, the mounting meansfor said device comprising interengaging bearing elements coaxial withand surrounding said screw and providing for rotation of said devicerelative to said bearing member, and a connection between said deviceand said screw which permits the device to move axially of said screwwhile rotating the same.

18. In a grinding machine, a base, a vertical column extending upwardfrom said base, a hearing member rotatably and slidably mounted on saidcolumn, a grinding wheel assembly includ ing a grinding wheel andmounted on said bearing member for movement in a circular path abovesaid base, a motor mounted on said bearing member for driving saidgrinding wheel, means tending to maintain said assembly at a normalposition in said path, a work support mounted on said base at adifferent position in said path, means including a second motor forlowering said bearing member on said column, a third motor for rotatingsaid work support, electrical circuits for said motors, means forclosing the circuit of said first motor, and switching means actuatedresponsive to rotation of said assembly about said column from saidnormal position to a position above said work support to close thecircuits of the said second and third motors, whereby the work supportis rotated and the grinding wheel is fed on to a work piece on saidsupport.

19. In a grinding machine, a base, a vertical column extending upwardfrom said base, a bearing member rotatably and slidably mounted on saidcolumn, a grinding wheel assembly including a grinding wheel and mountedon said bearing member for movement in a circular path above said base,a motor mounted on said bearing member and having a driving connectionto said grinding wheel, means having a connection to said assembly andtending to rotate the grinding wheel to a normal position in said path,latching mechanism operative to hold said assembly when the same isrotated to a position above a work piece supported on said base,automatic mechanism operating to cause said grinding wheel to perform apredetermined grinding operation on said work piece by lowering andraising said bear- 16 ing member on said column, and means may ing torelease said latching mechanism upon the completion or said grindingoperation.

20. In a grinding machine, a base, a vertical column extending upwardfrom said base, a baring member rotatably and slidably mounted on saidcolumn, a grinding wheel assembly including a grinding wheel and mountedon said hearing member for movement in a circular path above said base,a motor mounted on said hear ing member and having a driving connectionto said grinding wheel, means having a connection to said assembly andtending to rotate the grinding wheel to a normal position in mid path.iltdling mechanism operative to hold said assembly when the same isrotated to a position above a work piece supported on said base, and momnism for sliding said hearing member on mid column to move said grindingwheel in and all of operative relation to said work piece. mid mechanismincluding a lever pivoted on said base. a cam operatively engaging onearm of said lover. and a connection between the other arm of mid leverand said bearing member.

21. A grinding machine as claimed in claim 3.. wherein the connectionbetween the lever aland bearing member includes mechanism opera, tive toadjust the elevation ot the grinding Ilmd prior to starting the grindingoperation.

22. In a grinding machine, a base, a vertical column extending upwardfrom said base and having a finished external bearing surface, a bearingmember surrounding said column and rotatably and slidably engaging saidbearing surface, a grinding wheel and a driving motor therefor mountedon said bearing member, means comprising a thrust bearing, 0. microneterscrew coaxial with said column and a nut threaded on said screwsupporting said hearing member, said nut being fixed to said bearingmember, an adjusting device, bearing means supporting said device onsaid bearing member for rotation therewith when the bearing member isrotated on said thrust bearing, said bearing means providing forrotation of said device independent 01' said bearing member, and adriving connection between said device and screw to rotate the screw insaid nut to raise and lower the bearing member on said column.

23. In a grinding machine, a base, a vertical column extending upwardfrom said base, a bearing member rotatably and slidably mounted on saidcolumn, a grinding wheel assembly including a grinding wheel and mountedon said bearing member for movement in a circular path above said base,a motor mounted on said bearing member for driving said grinding wheel,a work support mounted on said base in the said path, means including arotatable cam for lowering and raising said bearing member on saidcolumn, said means also including a device operated by said cam andhaving an operative connection to said bearing member, a second motorfor rotating said cam, a circuit including said second motor and aswitch actuated to complete said circuit by movement of said grindingwheel assembly to a position above said work support, whereby saidgrinding wheel is fed on to a work piece on said support and then liftedtherefrom by rotation of said cam, and means operated by said secondmotor and efl'ective upon a complete rotation of said cam to open saidcircuit to stop said second motor.

ALFRED J. BOWEN.

(References on following page) References Cited in the file of thispatent Number 2,260,635 UNITED STATES PATENTS 2,297,078 Number Name Date2,345,986 1,326,091 Porter Dec. 23, 1919 5 2,414,560 1,717,345 Ripley 81a1. June 11, 1929 r 2 435 22 1,873,751 Fraser Aug. 23, 1932 1,888,710Arter et a1. Nov. 22, 1932 1,905,651 Raule Apr. 25, 1933 Number2,259,870 Ahnert Oct. 21, 1941 10 362,750

Name Date Musselman Oct. 28, 1941 Schlichter Sept. 29, 1942 Mentley eta1. 1.- Apr. 4, 1944 Rosmait Jan. 2'1, 1947 Fielding Feb. 10, 1948FOREIGN PATENTS Country Date Great Britain Dec. 10, 1931

